Speaking to GameSpot at PAX Aus, the game’s director Matt Firor told the publication that they had considered bringing the game onto the Switch, but it was literally too big for the console. According to Firor, “We have thought about Switch but ESO is an enormous game, and it just will not work. I would love for it to because I love Switch. It is one of the largest games ever made, and it just will not fit on Switch.”
The game weighs about 75GB which means that installing it on the Switch would be impossible given the console’s base storage, and presumably using a memory card might not be fast enough for the game to run from. That being said, Bethesda has not neglected the Switch and has brought various titles to the console, such as Skyrim which was one of the games shown off for the Switch when the console was first unveiled.